1. Technical Field
The invention relates generally to semiconductor devices, and more specifically, to variable power control for semiconductor devices.
2. Background Art
For battery applications for Application Specific Integrated Circuit (ASIC) devices, or similar semiconductor devices, low power usage is important. Semiconductor devices comprising transistors for driving a load for such devices should operate at their maximum speed. When the device is in stand-by mode, the transistors should be off. Also, depending on how much voltage is needed to drive a load, the device""s transistors should be able to provide that voltage without leaking too much current.
Examples of controlling the voltage through various transistors are found in the following U.S. Patents, which are hereby incorporated by reference: U.S. Pat. No. 5,682,118, xe2x80x9cCircuit for Controlling the Voltages Between Well and Sources of the Transistors of and MOS Logic Circuit, and System for Slaving the Power Supply to the Latter Including the Application Thereof,xe2x80x9d issued October 1997 to Kaenel et al.; U.S. Pat. No. 5,557,231, xe2x80x9cSemiconductor Device with Improved Substrate Bias Voltage Generating Circuit,xe2x80x9d issued September 1996 to Yamaguchi et al.; and U.S. Pat. No. 4,157,557, xe2x80x9cControl Circuit for Signal Transmission,xe2x80x9d issued June 1979 to Sato et al. Although each of the aforementioned patents disclose the control of voltage through transistors, they do not disclose how the transistor leakage current may be varied and controlled through geometric transistor properties (e.g., width, length, etc.).
It is thus an advantage of the present invention to provide a variable power device that eliminates the above-described and other limitations.
The advantages of the invention are realized by a variable power device circuit. The variable power device circuit comprises a plurality of devices for driving a load. Each of the devices has a body, which is electrically isolated from the substrate. All of the devices are coupled to an output node. The load is also coupled to the output node. A controller selectively turns on individual or multiple ones of the devices based on the electrical requirements of the load.
The foregoing and other advantages and features of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.